Due to the high plasticity and strength of copper and the self-lubricating function of lead, they are excellent wear antifriction material that have been tested and proved by practice and are widely used in the fields of precision machinery and aerospace. To study the effect of fraction of alloy element on the mechanical properties of copper-lead alloy during the nano-tensile process, a large-scale molecular dynamics simulation model of polycrystalline copper is structured by Poisson-Voronoi method and Monte Carlo method, and hybrid Monte Carlo/molecular dynamics (hybrid MC/MD) method is adopted to build the copper-lead alloy model. According to the real copper-lead materials, the model of copper-lead alloy with different element fraction and polycrystalline copper simulation are established. The nano-tensile process with different element fraction are simulated by molecular dynamics method, and the coordination number, internal stress and atomic potential energy of the atoms are calculated. The results show that there are significant regularities in the nano-tensile process of copper-lead alloy with different element fraction. The hydrostatic pressure and atomic potential energy distribution are similar between copper-lead alloy and polycrystalline copper, and lead atoms can suppress the dislocation of copper-lead alloy grain boundary, making the structure of grain boundary interface of the alloy material more stable. The variations of the potential energy of the grain cell and grain boundary interface during the plastic deformation of the alloy material is opposite. The fraction of lead atoms mainly affects the grain boundary interface state, and the grain boundary interface plays a major role in the plastic deformation process. Therefore, the properties of the alloy materials can be changed by changing the fraction of elements in copper-lead alloy. The research results in this paper provide some theoretical guidance for the preparation of high-performance copper-lead alloy materials.